This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. MK-0752 will be administered orally for 3 consecutive days of every 7 days for 28 days to children with recurrent or refractory central nervous system (CNS) malignancies. The starting dose is 200 mg/m2/day and inter-patient dose escalation or reduction will occur in set increments (to an estimated maximum of 400mg/m2/day). At the recommended MTD, we will treat a minimum of 6 evaluable patients who are <12 years of age. Although the dose escalation will be based on toxicities observed during the first course, any grade 3/4 toxicities that occur after the first course will be documented and may warrant a review of the treatment regimen. Therapy may continue for 6 courses. If patients are deriving benefit from the therapy and have at least clinical and radiographic stable disease at the end of course 6, patients may continue therapy for an additional 13 courses (for a total of 19 courses) with the prior approval of the study Chair and representatives from Merck and Co. MK-0752 will have anti-tumor activity in children and adolescents with refractory primary CNS tumors. PRIMARY OBJECTIVES To estimate the MTD and recommend a Phase II dose of MK-0752 administered for 3 consecutive days of every 7 days for 28 days to children with recurrent or refractory central nervous system (CNS) malignancies.